This section is intended to provide a background or context to the disclosed embodiments. The description herein may include subject matter that could be pursued, but which has not necessarily been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems.
In conventional wireless networks, data and control signals are confined to the same carrier. In these systems, a wireless terminal can decode the control information in a downlink carrier to determine which of the data resources transmitted on the carrier are allocated to the wireless terminal. The wireless terminal also uses the control information to determine the uplink resources that have been granted to the wireless terminal by the base station serving the wireless terminal. For example, in Release 8 of the 3GPP (Third Generation Partnership Project) LTE (Long Term Evolution) standard, each subframe of the downlink carrier includes a physical downlink control channel (PDCCH) and a physical downlink shared data channel (PDSDCH). The PDCCH includes a control format indicator (CFI), in a downlink control format indicator channel (PDCFICH) at the beginning of the subframe, that identifies the duration of the PDCCH by the number of symbols it occupies in the time domain. Using this information, the wireless terminal knows where the control channel ends and the data channel begins.